I can read the last paragraph of A River Runs Through It any time and get goose bumps ("I am haunted by waters"). Gatsby has a great ending too. I'm talking about the writing, not necessarily the actual story in both cases.
I make a point of not reading ahead in any book. I hate having the plot spoiled for me. Sometimes I even have to cover up the facing page to avoid reading ahead unintentionally! I find that if I know how the story ends, I'm less interested in what happens to get to the ending.